NATURAL SELl'XTION 97 



lected character in some peculiar and filling manner ; he feeds 

 a long and a short beaked pigeon on the same food ; he does 

 not exercise a long-backed or long-legged quadruped in any 

 peculiar manner ; he exposes sheep with long and short wool 

 to the same climate. He does not allow the most vigorous 

 males to struggle for the females. He does not rigidly de- 

 stroy all inferior animals, but protects during each varying 

 season, as far as lies in his power, all his productions. He 

 often begins his selection by some half-monstrous form ; or 

 at least by some modification prominent enough to catch the 

 eye or to be plainly useful to him. Under nature, the slight- 

 est differences of structure or constitution may well turn the 

 nicely-balanced scale in the struggle for life, and so be pre- 

 served. How fleeting are the wishes and efforts of man ! 

 how short his time ! and consequently how poor will be his 

 results, compared with those accumulated by Nature during 

 whole geological periods? Can we wonder, then, that Na- 

 ture's productions should be far "truer" in character than 

 man's productions ; that they should be infinitely better 

 adapted to the most complex conditions of life, and should 

 plainly bear the stamp of far higher workmanship ? 



It may metaphorically be said that natural selection is daily 

 and hourly scrutinising, throughout the world, the slightest 

 variations; rejecting those that are bad, preserving and add- 

 ing up all that are good; silently and insensibly working, 

 whenever and wherever opportunity offers, at the improve- 

 ment of each organic being in relation to its organic and in- 

 organic conditions of life. We see nothing of these slow 

 changes in progress, until the hand of time has marked the 

 lapse of ages, and then so imperfect is our view into long- 

 past geological ages, that we see only that the forms of life 

 are now different from what they formerly were. 



In order that any great amount of modification should be 

 effected in a species, a variety when once formed must again, 

 perhaps after a long interval of time, vary or present indi- 

 vidual differences of the same favourable nature as before ; 

 and these must be again preserved, and so onwards step by 

 step. Seeing that individual differences of the same kind 

 perpetually recur, this can hardly be considered as an unwar- 

 rantable assumption. But whether it is true, we can judge 



D— lie XI 



